Spatially Separated Redox Cocatalysts on Ferroelectric Nanoplates for Improved Piezophotocatalytic CO 2 Reduction and H 2 O Oxidation.

Utilizing solar and mechanical vibration energy for catalytic CO 2 reduction and H 2 O oxidation is emerging as a promising way to simultaneously generate renewable energy and mitigate climate change, making it possible to integrate two energy resources into a reaction system for artificial piezophotosynthesis. However, the practical applications are hindered by undesirable charge recombination and sluggish surface reaction in the photocatalytic and piezocatalytic processes. This study proposes a dual cocatalyst strategy to overcome these obstacles and improve the piezophotocatalytic performance of ferroelectrics in overall redox reactions. With the photodeposition of AuCu reduction and MnO x oxidation cocatalysts on oppositely poled facets of PbTiO 3 nanoplates, band bending occurs along with the formation of built-in electric fields on the semiconductor-cocatalyst interfaces, which, together with an intrinsic ferroelectric field, piezoelectric polarization field, and band tilting in the bulk of PbTiO 3 , provide strong driving forces for the directional drift of piezo- and photogenerated electrons and holes toward AuCu and MnO x , respectively. Besides, AuCu and MnO x enrich the active sites for surface reactions, significantly reducing the rate-determining barrier for CO 2 -to-CO and H 2 O-to-O 2 transformation, respectively. Benefiting from these features, AuCu/PbTiO 3 /MnO x delivers remarkably improved charge separation efficiencies and significantly enhanced piezophotocatalytic activities in CO and O 2 generation. This strategy opens a door for the better coupling of photocatalysis and piezocatalysis to promote the conversion of CO 2 with H 2 O.